A typical wet, multicell, lead-acid SLI storage battery is assembled from an open-topped, rectangular-shaped container which is sealed by a cover assembly. Both portions are formed from an injection molded thermoplastic polymer, such as polypropylene. The container and cover have partition walls which divide the space within the battery into a plurality of substantially isolated cell cavities. Each cell cavity contains an electrode stack which is immersed in electrolyte. The cover typically defines a plurality of generally cylindrically shaped process holes, one associated with each cell cavity, through which the cell cavities are initially filled with electrolyte. In maintenance batteries, the process holes are closed-off by plugs which can be removed so that electrolyte can be periodically added through the process holes for maintenance purposes.
Especially during charging, lead-acid storage batteries generate various gases in the cell cavities during operation, including hydrogen and oxygen. Hydrogen/oxygen mixtures create an obvious potential for explosion. In recombinant lead-acid batteries, hydrogen and oxygen gas is retained in large part in the battery and induced to recombine into water. In wet lead-acid storage batteries, however, such gases are allowed to escape from the cell cavity and ultimately pass out of the battery through a venting system.
There are a wide variety of known venting systems for expelling the volatile gases generated within a wet battery to the external, ambient space. In general, each particular configuration is directed to achieve a dual purpose: allowing gases to vent from within the battery, while retaining the electrolyte fluid therein.
That is, wet, lead-acid storage batteries are used in a tremendous variety of vehicles and applications. As a result such batteries are often subject to extreme and harsh operating environments. For example, batteries used in land moving vehicles such as bulldozers are frequently tilted at severe angles, as well as being subjected to intense operating vibrations. It is, therefore, apparent that electrolyte can splash about the interior of a battery during normal battery use, as well as during installation and shipment. To the extent that electrolyte can leak from the battery, however, the electrochemical performance of the battery may suffer. Accordingly, venting systems in wet lead-acid batteries are designed to retain the electrolyte within the battery cells, while at the same time freely allowing for the escape of gases generated within the cells.
As noted, there are a wide variety of venting systems presently employed in lead-acid storage batteries. Many of those venting systems, however, are unduly complex and, accordingly, excessively costly. Despite the continuing effort in this area there remains a need for batteries which have relatively simple venting systems which efficiently retain electrolyte while effectively venting gases in a relatively safe manner, but which can be easily and economically manufactured.
Accordingly, it is a primary object of the present invention to provide a battery having a venting system which is easily and economically manufactured.
It also is an object to provide a battery which vents gases generated with the cell cavities in a safe and efficient manner.
Another object of the present invention is to provide a battery having a venting system that minimizes the escape of electrolyte, even when the battery is vibrated or tilted at extreme angles.
Yet another object is to provide a battery wherein all of the above advantages are realized.
Additional objects, advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention.